Others have developed solutions for two touchdown testing of 300 mm wafers containing many NAND dice, e.g. 432 NAND dice having 16 test sites each for a total of 6912 test sites. Generally, this type of testing utilizes mechanical relays installed in the device under test (DUT) interface of the automatic test equipment (ATE) system. These relays are typically located electrically far away from the device under test (DUT). This distance may create a large impedance mismatch when reading back from the device. In addition, the maximum data rate for testing the device may be limited to only 20 MHz.
Mechanical relays are also quite expensive. For example, the typical mechanical relays may each cost about $8.00. This may limit the return on investment (ROI) for the customer. Mechanical relays are generally rated for about 1 to 10 million test cycles. This may create reliability issues for the customer over time. Furthermore, mechanical relays are only rated for operation up to 85° C. This allows testing of NAND devices using mechanical relays at or below 85° C.
Other solutions for multiplexing a large number of tester pin electronics (PE) by mounting a plurality of daughter boards on probe cards. This will only allow two touchdown testing of 300 mm wafers of NAND dice. This daughter card approach has limitations with respect to temperature and density. The connector limits the density of switches that can be placed on the daughter card and the active silicon switches have a temperature limitation of 85° C. when using standard grade integrated chips.